1. Field of the Invention
This invention relates to novel unnatural sex attractant compositions and use thereof to attract pink bollworms and pinkspotted bollworms in fields treated with the Z,Z- or Z,E-isomer of 7,11-hexadecadien-1-ol acetate. More particularly, the invention provides means for altering the preference of the male pink bollworm or pinkspotted bollworm away from the sex pheromone emitted by the female of the species and to the novel compositions of the invention.
2. Description of the Prior Art
The pink bollworm, Pectinophora gossypiella (Saunders) is an economically important field pest afflicting cotton production throughout the world. The pink bollworm larvae feed on buds, flowers, and bolls of the cotton plant, and because of their widespread distribution, voracious appetite, and enormous population cause severe economic losses to cotton growers.
While chemical pesticides are useful in the control of the pink bollworm, use of widespread broadcasting of insecticides has the disadvantages of destruction of desirable predators and parasites which aid in the control of Heliothis virescens, particularly when used early in the growing season; development of insecticide-resistant pink bollworm populations; toxicity to man and animals; contamination of the environment., and expense of application.
The continued search for alternatives to the widespread application of insecticides has led to the investigation of sex attractants as agents for use in integrated pest management programs. A number of economically important insects are currently monitored, partially controlled, or completely controlled by use of their own specific pheroaone.
The pink bollworm sex pheromone has been identified as about a 1:1 mixture of the Z,Z- and Z,E-isomers of 7,11-hexadecadien-1-ol acetate, hereinafter termed gossyplure (Science 181:873-875 (1973)). Gossyplure has been successfully used for sexual communication disruption between adult moths resulting in the reduction of larvae infesting cotton bolls (Science 196:904-905 (1977)). Gossyplure is theorized to work in either of two ways (1) false trail following wherein males spend their time following pheromone trails released from the applied sources and (2) adaptation of the antennal receptor sites or habituation of the central nervous system (CNS). To be effective for false trail following, the applied sources must be in numbers far exceeding the numbers of female pink bollworms that are emitting the pheromone such that the chance of a male finding a female instead of a source is low and the emission rate of the sources must be high enough to be conspicuous in the low ambient background of gossyplure from all the other sources. In the adaptation and habituation responses, it is theorized that if enough gossyplure is released into the atmosphere, the attennal receptor sites become adapted and fail to send out the usual electrical signal. Also, when the antennal receptor sites are continually sending electrical impulses to the CNS, the CNS becomes habituated and the insect may no longer respond with the normal behavior.
The primary disadvantages of using gossyplure sources are (1) that males are seeking gossyplure-emitting sources and thus may encounter female moths (that also emit gossyplure) and mate, and (2) that reduction of mating is not sufficient, particularly when populations of the pink bollworm are greater than ten percent in the cotton bolls. While use of an insecticide in combination with gossyplure improves the efficacy through the debilitation or killing of male moths attracted to the pheromone-baited dispensers and contacting the insecticide, there have been problems attaining the desired efficacy of annihilation, i.e., removal of 95% of the males, with this method. Additionally, since the males are seeking gossyplure-emitting sources, they may encounter females and mate.
Flint and Merkle (Journal of Economic Entomology 76:40-46 (1983)) disclose the use of the individual component isomers of gossyplure to disrupt sexual communication between male and female pink bollworm moths as determined by reduction in trap catch and mating in field plots. Because males do not usually contact sources of individual component isomers of gossYplure, the combining of an individual isomer with an insecticide has little or no value in annihilation of the male moth.
The pinkspotted bollworm, Pectinophora scutigera (Holdaway), is associated with various native malvaceous plants in Australia and the adjacent Pacific region and is also the primary pest of cotton in central Queensland. Because the area for cotton growing in Queensland and northern New South Wales has been significantly increased recently, there is concern that the pinkspotted bollworm may be transmitted outside its present limited range and become a more serious problem (Rothchild, Journal of the Australian Entomological Society 22:161-166 (1983)). While the components of the pinkspotted bollworm pheromone are not known with certainty, trap catch data suggests that it is about 10:1 ratio of Z,Z- to Z,E-isomer of 7,11-hexadecadien-1-ol acetate (Rothchild, Environmental Entomology 4:983-985 (1975)). Use of sex attractants having a composition or attraction properties similar to that of the natural pheromone to monitor or control the pinkspotted bollworm has the disadvantage that the males may encounter female moths and mate.